How about this perspective? You are being tracked regardless. Do you have friends? Do they have your number? You have a tracking ID. Have you ever used the Internet at home not on a VPN and not on a fingerprint-preventing browser (i.e. JavaScript off)? You have a tracking ID.

This tracking ID is surrounded by data it gathers from your interactions with others, regardless of whether you want it to or not. Your lack of presence here is far more telling than actually existing. Unless you literally live off the grid no contact, there's no getting away from it.

On the bright side, guess what? These tracking IDs are practically solely for advertising metrics. The chances of any of this data being meaningful beyond "vestmoria likes vintage cheeses after" is pretty much nil. I would even go so far as to say by having a presence in this space you are likely to be less targeted by prying eyes that actually matter, as opposed to right now where you are a clearly visible dark spot in a sea of lit beacons.

To put it another way - privacy now is through obfuscation, not lack of existence. Google solved the dumb-phone problem in 2013 and they have had advertising IDs on these from the moment they get used. They have had your data already for a long, long time now. Your advertising ID is better used clicking on every ad you come across using AdNauseam than it is trying to de-google a smartphone or avoid carrier data. Make the data on you inaccurate and worthless.

If you really want to avoid using tracking aspects of a smartphone, your best bet is convincing your people to download signal or matrix and use them exclusively, with notifications turned off on the phone. You'll want to run a VPN you trust. Others suggested custom ROMs to get away from Google, though I'm personally no fan of MicroG either.

I think it's worth considering accepting that unless you are very specific in how you use it, there is no real feasible way to not be tracked. Even if you take all precautions, even then, you are still being tracked by other peoples phones. With that in mind, your mental health should be put at ease knowing that rather than trying to avoid it, there are ways of feeding it dirty data to make you look like everyone else.

Using Linux you probably already are aware of quite a bit of this, but I've always felt that being off the grid or off the radar of adver-govs is a false hope and while there may be measures against it there's nothing that actually prevents it in full and it's so much more effort than allowing it to happen but lying about yourself. So what if they have data on you if it's irrelevant! On top of that, what does it matter if your calls have data on them (date/length). The content of the calls is a different story of course, I don't have a solution for that.

Maybe you can fake phone calls by spoofing phone models and locations and having their conversations spoken via AI.